Microelectromechanical systems (MEMS) have been developed as alternatives to conventional electromechanical devices, such as relays, actuators, valves and sensors. MEMS devices are potentially low-cost devices, due to the use of microelectronic fabrication techniques. New functionality also may be provided, because MEMS devices can be much smaller than conventional electromechanical devices.
A major breakthrough in MEMS devices is described in U.S. Pat. 5,909,078 entitled Thermal Arched Beam Microelectromechanical Actuators to the present inventor et al., the disclosure of which is hereby incorporated herein by reference. Disclosed is a family of thermal arched beam microelectromechanical actuators that include an arched beam which extends between spaced apart supports on a microelectronic substrate. The arched beam expands upon application of heat thereto. Means are provided for applying beat to the arched beam to cause farther arching of the beam as a result of thermal expansion thereof, to thereby cause displacement of the arched beam.
Unexpectedly, when used as a microelectromechanical actuator, thermal expansion of the arched beam can create relatively large displacement and relatively large forces while consuming reasonable power. A coupler can be used to mechanically couple multiple arched beams. At least one compensating arched beam also can be included which is arched in a second direction opposite to the multiple arched beams and also is mechanically coupled to the coupler. The compensating arched beams can compensate for ambient temperature or other effects to allow for self-compensating actuators and sensors. Thermal arched beams can be used to provide actuators, relays, sensors, microvalves and other MEMS devices. Other thermal arched beam microelectromechanical devices and associated fabrication methods are described in U.S. Pat. No. 5,994,816 to Dhuler et al. entitled Thermal Arched Beam Microelectromechanical Devices and Associated Fabrication Methods, the disclosure of which is hereby incorporated herein by reference.
As MEMS devices become more sophisticated, there continues to be a need for MEMS structures that can be used in more sophisticated MEMS devices. Fabrication of these structures preferably should be accomplished using conventional MEMS fabrication process steps.